Team Members: Kyle Bloomer Josh Geiman Lucas Bennett Potentiostat Team Members: Kyle Bloomer Josh Geiman Lucas Bennett Team Sponsor: Dr. Cindy Harnett Team Mentor: Dr. Andy Dozier

Harnett Lab Dr. Harnett's laboratory needs 15 potentiostats for her microfluidics lab Off the shelf potentiostats range in price from $5K to $10K, which is prohibitive for an instructional lab Commercial Potentiostat

What is a Potentiostat? A Potentiostat is an instrument that is used to characterize electrochemical reactions Fuel cells – reacts liquid fuel and oxidizer to produce electricity Gas generators – Uses electrolysis to generate gas A potentiostat measures the voltage difference between a Working Electrode and a Reference Electrode Three electrode configuration Most commercial potentiostats provide a second mode of operation that measures the current flow between the Working and Counter Electrodes This mode is known as a “galvanostat”

History - Ardustat A previous potentiostat was attempted by a project team using an open source design, the Ardustat The Ardustat was a two electrode configuration Ardustat electrical design was poorly documented, which caused the project team to have difficulty implementing it for the project Software design was “spaghetti code”, and it had no documentation or comments for either the firmware or the application software Hardware used was an Arduino processor board, with a prototype “daughter board” The team was unable to meet the project goals

Ardustat Hardware

Ardustat GUI – Connect & Setup

Ardustat GUI – Data Logging

Ardustat Code Example Show pictures of GUI or firmware code Before Ben After Ben

Previous Project Diagram

Previous Project Test Set

Current Status An MEng student has implemented the hardware using a PCB assembly, and gotten it to work The existing code has been reverse engineered and documented/commented BUT the Ardustat is a two electrode configuration, and the software GUI is very limited in its capabilities

Research We have found an open source, three electrode potentiostat, known as the “Cheapstat” Cheapstat was developed by UC Santa Barbara to provide an affordable alternative to COTS potentiostats

Cheapstat Features Input parameters must be set through an onboard LCD and 5-way joystick The display is very limited LCD on the Cheapstat processor “box” Provides multiple measurement modes List the modes here

Cheapstat Hardware Front Panel PCB Assembly JoyStick To Cell Electrodes

Design Goals - Hardware Design and implement a three electrode potentiostat, based on the Cheapstat Three electrode design Easier to use interfaces GUI on a PC No joystick Ease of assembly and use by students, faculty, and staff PCB assembly techniques USB processor to PC interface External power sources Full documentation of hardware Schematics Simulation results Assembly diagrams List of Materials

Design Goals - Software Develop GUI and firmware using modern software engineering techniques No spaghetti code Comment all code Provide a software library Document all the application software and firmware Installation notes User’s Manual

Project Goals - Other Characterize electrical performance for a typical electrochemical device Compare electrical measurements with the existing Ardustat Two electrode vs. three electrode measurement differences

System Diagram

Major Components Processor Display/Data Management System (DDMS) Firmware Display/Data Management System (DDMS) GUI software Power supply

System Diagram

Processor Requirements Capture the test configuration Measurements to be made, ranges, etc. Execute the test using the measurements that have been established by the operator Log and time stamp test results in NVRAM Send measurement data to Display/Data Management System (DDMS) during test When polled by the DDMS, send the test results in CSV format to a file on the PC

System Diagram

DDMS Requirements Pre- test Mode Test Mode Post Processing Calibrate instrument Configure processor for the test to be executed Test Mode Execute test script that was entered during Pre-Test Display results during test Post Processing Report generation

GUI Mockup

System Diagram

Voltage Converter Three options are available: Wall Wart USB Battery power Microprocessor requires 5 VDC Estimated 3 watts

Current Status Build and test Cheapstat using current design CheapStat Parts have been ordered Research ongoing regarding firmware development environment Software development kit to preserve schedule Test existing Ardustat Need DUT – Chlorine Generator?

Questions?